Intramolecular Diels−Alder Reactions of Ester-Linked 1,3,8-Nonatrienes

Penta-1,3-dienyl acrylates undergo kinetically controlled intramolecular Diels−Alder (IMDA)
reactions and DFT calculations (B3LYP/6-31+G(d)) predict stereoselectivities that are in very good
agreement with the experimental values. The nature of the diene C1 substituent has virtually no
influence upon reactivity or trans/cis-stereoselectivity whereas terminal C9 dienophile substituents
have a substantial effect on both the reactivity and stereoselectivity of these IMDA reactions. The
TSs highlight contributions from strain in the developing tether-containing ring, and steric and
electronic effects between tether and dienophile substituents, thus providing insight into the origins
of IMDA reactivity and stereoselectivity.